Hi, I tried search,and no luck.. if I missed something,please let me know...
I just both a great shape Civic SIR with only 116000 km.

last owner replaced stock exhaust with a 2.5 in, Resonator (cat removed) and headers,After that errors started to come up for both sensors.
He replaced both o2 sensors for 3 times... and every time after a while, errors for both kept coming back...
just to make sure, I did the same, installed 2 brand new ones (300$)
and after 30 km, the same thing... what could be the reason for this,
PLEASE help...

PS. for about 29 km I did not push it,and it was fine,then did 5-6 hard starts 0-60 ,and after 2 min. the CEL lit again.
Thank you in advance guys!

 

There's your problem.

 

what exactly is the problem if you can explain please... ?

 

Was working fine before he did this?
Have you checked for exhaust leaks?

 

that's what he told me, yes.
He seemed like a really honest guy.
any idea on how to solve this... ?

 

You don't have a catalytic converter so the o2 sensors are getting funky readings thus throwing a CEL. Slap cat back on it and I'm 99% sure it will fix the issue

 

I was hoping to keep my engine breathing easier, it has AEM intake, headers open flow exhaust, no cat ....
Any other solution maybe... its hard to believe that anyone with open exhaust and no cat, has these problems...
there's got to be some other solution to this...

 

The primary O2 sensor doesn't care about a cat, it only cares about engine efficiency. The secondary O2 sensor only cares about the efficiency of the cat. OP, you need to tell us exactly WHAT code you're throwing.

 

what exact codes are you throwing? in an OBDII equipped vehicle, the rear O2 monitors catalyst efficiency, so a CEL will be triggered if the cat is gutted or removed. this is why they have "o2 sensor simulators" for sale which are basically spark plug defoulers that you can get at autozone for $5.

 

still trying to find the "blue connector" ,from my last post...
as I mentioned, just bought the car couple days ago... it does not look like its under the gloves compartment...
The old owner just mentioned that the errors they found in the mechanics shop
ware for both faulty sensors :S
Il try and find the blue connector and get back to you guys with the exact code
Thank you!

 

^

The service connector is above the ECU. Remove the passenger kick panel.

 

 

Hi!
Finally!!
Been working a lot,Sorry for the delay.
CEL: 67
ABS light: 54
Idk if that has anything to do with Engine...but its blinking ,so just to mention it...
If anyone knows what could help, I would really appreciate it. Thank you.
UPDATE of all errors till today:
First error, after changing both sensors: -30 km
Second error, drive it to work and back,really easy,maybe 3-4 harder starts and over 180 kmh: -90 km
Third error, highway travel: -about 120 km

 

Buy a cat. There are high flow cats that do not restrict the exhaust.

 

I would really like to keep open exhaust... And I read that the same thing is known to
happen to people with high flow cats...
If that is true, I would rather spend that money on something that would solve the problem for sure...

 

Get a good high flow cat that is properly spec'd for your exhaust size, not a cheap parts store unit and deff not a cheapo eBay unit.. Stop driving a civic with a straight pipe plz. Exhaust gases without a car are bad for earth, man.

you could try the defouler trick someone mentioned earlier

 

What is that exactly... o2 sensor simulators who simulate o2... but is that the best solution... wouldn't the car run lean ,or rich or whatever...?
Any recommendation on hi flow cats for 2.5 in exhaust ...?

 

You don't need an O2 simulator. Those are fancy electronics that are stupidly expensive, and actually send the right thing to the ECU. It's a misnomer. What you want are two spark plug defoulers. They're cheap. You can get them from Autozone.

 

I would look on summit, they usually stock parts that aren't too crappy.

notaracist, that trick requires the services of a welder if I'm not mistaken, right?

p.s. This is why obd1 kicks ***

 

Nope, no welding required.

 

no welding. only a drill and a 1/2" bit iirc

 

here you go: http://forums.evolutionm.net/evo-how...ouler-how.html

 

Thanks Everyone... but I have that thing installed on the car already from the last owner...
When I saw the pics from @eghatch ,I recognized it
and still CEL is coming up....
The only difference is that its not drilled,its a small original hole, and its a one peace
PS.
threads are bad where the sensors are screwed in.. but Iv tighten it pretty hard...so I doubt that there is any "leaking" ,and whole exhaust is looking mint.

 

so you guys say,its definitely the downstream sensor,not the upstream one..? (they are both new)
What is the best thing to do regarding the performance ...I really want to have a full breathing B16...?

 

http://m.ebay.com/itm/2-5-Magnaflow-...-/170862884170

a catalytic converter that has "high flow" written on the box. I would call magnaflow first and ask if that seller is actually really authorized to sell em and also read their reviews, since its eBay. Or look on summit